我有简单的jsf app和servlet用于动态图像和过滤器设置utf8编码。不时（1/10请求）我得到了非常奇怪的错误：
WARNING: StandardWrapperValve[com.webapp.servlet.ImageServlet]: PWC1406: Servlet.service() for servlet com.webapp.servlet.ImageServlet threw exception
java.lang.NullPointerException
at com.sun.enterprise.v3.services.impl.monitor.MonitorableSelectionKeyHandler$CloseHandler.notifyClosed(MonitorableSelectionKeyHandler.java:94)
at com.sun.enterprise.v3.services.impl.monitor.MonitorableSelectionKeyHandler$CloseHandler.remotlyClosed(MonitorableSelectionKeyHandler.java:90)
at com.sun.grizzly.BaseSelectionKeyHandler.notifyRemotlyClose(BaseSelectionKeyHandler.java:233)
at com.sun.grizzly.util.OutputWriter.notifyRemotelyClosed(OutputWriter.java:353)
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:148)
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:76)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flushChannel(SocketChannelOutputBuffer.java:326)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flushBuffer(SocketChannelOutputBuffer.java:398)
at com.sun.grizzly.http.SocketChannelOutputBuffer.flush(SocketChannelOutputBuffer.java:376)
at com.sun.grizzly.http.ProcessorTask.action(ProcessorTask.java:1247)
at com.sun.grizzly.tcp.Response.action(Response.java:268)
at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:380)
at org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:353)
at org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:175)
* at com.webapp.servlet.ImageServlet.doGet(ImageServlet.java:35)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
at com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:118)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
* at com.webapp.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:32)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
这是我的servlet和过滤器，我标有引用stacktrace的星号行：
@WebServlet(urlPatterns = "/images/*")
public class ImageServlet extends HttpServlet {
@Inject
private FileService fileService;
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
byte[] img = fileService.getImage(request.getPathInfo());
if (img != null) {
response.setContentType("image/png");
response.addHeader("Content-Length", String.valueOf(img.length));
ServletOutputStream os = response.getOutputStream();
os.write(img);
* os.flush();
os.close();
} else {
response.sendRedirect(request.getContextPath() + "/error");
}
}
}
@WebFilter(urlPatterns = "/*")
public class CharacterEncodingFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
* chain.doFilter(request, response);
}
@Override
public void destroy() {
}
}
我完全不知道发生了什么......我正在使用带有jdk7的Glassfish 3.1.1网络配置文件
答案 0 :(得分：2)
关闭流时已隐式执行刷新。关闭已经由容器本身隐式完成。实际上你不需要自己做。但是，大多数servlet开发人员这样做是为了对他们忽略的情况提供早期反馈，即请求 - 响应链中的其他内容正在写入输出流，例如：一个错误的过滤器或响应包装器或东西。这将导致每次调用IOException，因为流已关闭。
在任何情况下，您都有2个选项来处理flush()和close()：
try-catch中，您忽略该异常。 此异常仅表示客户端中止了连接。例如。按下[Esc]或关闭窗口/标签，或在图像仍在流式传输时导航到其他页面。
答案 1 :(得分：0)
at com.sun.grizzly.util.OutputWriter.notifyRemotelyClosed()
不知何故，这看起来好像你正在刷新流的连接已经被远程对等体（Web浏览器？）中间关闭了。
您可以试试response.flushBuffer()吗？这是否也会抛出异常？